Wetand News

This is not an April fools prank. A shot of cold air will push into western Washington late Tuesday and Wednesday, with strong northeasterly winds from the Fraser River Valley extending into northwest Washington, and even a chance some of you will spot some snowflakes.  In April. The predicted surface weather map for 8 AM April 1st is, well, chilling.  Very cold air (purple/blue colors) is pushing into southern British Columbia, with a low center near the Columbia River bars.  If this was January, I would getting my snow shovel handy. With cold, dense air and high pressure in southern BC and low pressure over southwest Washington, a large pressure difference (gradient) will develop over the Fraser River Valley,  accelerating cold air into Bellingham and NW Washington.  This is shown by wind gust forecast for 8 AM Wednesday, with winds reaching 35 knots.  The northeasterly flow will then run into the Olympic Peninsula...and as we shall see, bringing low-level snow. Later i

We all need some good news and I will give that to you.  The weather is going to improve by next weekend here in the Northwest.  Much warmer and even some sun. But there is also some bad news....we will have to get through a cool/cloudy period first. Let's face it.  It has been cool and murky this week, a situation that heightened the stress of all the virus news.  Below are the temperatures at SeaTac during the past two weeks, with the normal highs and lows plotted.  Our daily maximum temperatures have been well below normal the last six days.   Like 5-10F below normal.  Plus lots of clouds and light rain. Tomorrow will be similar and then a much stronger system, with real rain, will hit Monday, associated an unusually energetic upper level trough (see upper level map for 5 PM Monday).   If this was January, we would be worried about lowland snow with such a pattern. Fortunately, as the week progresses an upper level ridge of high pressure will build along the W

Weather prediction is an essential technology that both protects the economy and saves lives. National Weather Service personnel are considered critical personnel and are still working, but they are dependent on numerical weather prediction models, which in turn are dependent on the quality and quantity of weather data going into them. And it appears that one important data source is declining rapidly in volume, aircraft observations. And such observations are particularly important for the West Coast of the U.S., which has a vast ocean to our west. To produce a numerical weather prediction, a three-dimensional description of the atmosphere needs to be created, something called the initialization . Over land there are lots of surface observations and balloon-launched weather observations (radiosondes), but obviously there are far fewer of these  over the ocean.  In the old days of numerical weather prediction, forecast skill was less downstream of oceans because of the large

Since many are stuck at home, I thought it would be fun and useful to provide a forecast discussion with lots of images and graphics.  Check it out and let me know if you want me to do it regularly. My next version will be at higher resolution.  And I am thinking of doing one where I can interactively answer weather questions....just need to figure out how to do that.....

There is an extraordinary video on the front page of BING right now ( https://www.bing.com/ ) Gorgeous, multi-level lenticular clouds. Watch it carefully.     There is a multi-level stack of several lenticular (mountain wave) clouds, reflecting the complex structure of moisture approaching the mountain. You can see how turbulent the lower portion of the lenticular cloud stack is. Thanks to Professor Arthur Nowell for bringing this video to my attention.

I have gotten a number of emails from folks wondering whether the local air quality has improved as many of us stay home from work and other activities. As I will show in a minute, there is no obvious evidence of better air quality this week, and, in fact, during the past days the air quality has declined to moderate in some areas. This morning, the U.S. EPA AirNow website showed a region of moderate air quality (yellow colors) over western B.C., Washington, and Oregon. During the day, with a warming sun and better mixing, things improved substantially Taking a look of a plot of air quality during the past week at Seattle (blue), Tacoma (red), Spokane (tan), and Marysville (purple), there are good levels (below 50) for Monday through Friday, but moving into the moderate zone last night.  The substantial daily (diurnal) variations are obvious. Air quality got better each day as solar heating causes the atmosphere to become well mixed. Perhaps we can get some insights

To start on a positive note, the Cherry Blossoms are in full bloom on the UW Campus, with the visual effect enhanced by the beautiful, sunny weather.  (I should note that the UW is not encouraging folks to visit the blosssoms in person). There is a lot of interest in the temperature/coronavirus relationship and what the weather forecasts suggest. During the past several weeks there have been several papers submitted (but not yet reviewed) suggesting that coronavirus flourishes for daily mean temperatures roughly from 32F to 55F.  Warmer than that, the virus has problems. The temperature map for the past month suggests that the only area of the U.S. that has been at sufficiently warm (14C--57F or more) to slow up the virus was the southeast U.S. (see below). Unfortunately, the latest forecasts do not offer warm-temperature virus relief for much of the country during the next week.  Let me show that by presenting the 11 AM PDT temperatures for the next few days.  Look for

During another time you might feel very sorry for the poor folks vacationing on Kauai.   Instead of enjoying their Ma Tais under sunny skies and modest trade winds, they are suffering from heavy rains, very strong southerly winds, severe thunderstorm, and unusual tornado warnings The cause of this bounty of inclement weather?    A very large Kona Storm . A Kona storm (or Kona Low) is a low pressure center that develops to the west or southwest of the Hawaiian islands that bring moist, cloudy, or unstable air into the Hawaiian islands.  Associated with low-level winds from the south to west, Kona lows can bring rain to the western and southwestern ("kona") sides of the islands that are normally rainshadowed by the terrain.  Typically trade winds are from the east to northeast, thus the eastern/northeastern sides are typically the wettest. Here is a satellite image of the situation on Tuesday.  You can see the swirl of clouds around the Kona Low and a large band of rain (

Will the coronavirus decline as summer approaches?    What is its sensitivity to temperature, humidity, solar radiation and other factors? There is some scientific literature on this topic and more is being submitted.    I will summarize a few of them below, but let me give you the bottom line:  it appears that warm temperatures and high humidity is bad for the virus (or similar viruses).  Also ultraviolet radiation from the sun is problematic for the virus.  Thus, in many populated locations in the northern hemisphere, the virus will experience a less favorable environment. A recent submission to the journal SSRN by Sajadi et al. ( Temperature and latitude analysis to predict potential spread and seasonality for COVID-19 ) suggests for the coronavirus there is  "significant community spread in cities and regions only along a narrow east west distribution roughly along the 30-50 N corridor at consistently similar weather patterns (5-11C and low specific and absolute h

Washington State has immense resources to apply to the coronavirus crisis . One of the leading university medical centers in the world. Major biotech firms and a huge foundation dedicated to health science (Gates Foundation) The world's leading logistics and delivery firm (Amazon). One of leading brick and mortar food and supply firms (Costco) World-leading software and machine learning firms and expertise (e.g., Microsoft, Amazon) One of the leading tech centers in the world. Our state has intellectual, scientific, technological, and financial resources equivalent to those of many nations. Might we take a leadership role in tackling this crisis, not only for ourselves, but for the rest of the world as well?  Could Washington State lead the nation in heavily investing in a complementary approach to social distancing, online learning, and sending people home from work?    Might Washington State fill the void left by an ineffective Federal response? Importantly, coul